1. Field of the Invention
The present invention relates to an endoscope treatment tool used to excise a living body tissue or the like.
This application is a continuation claiming priority on the basis of Japanese Patent Application No. 2012-198814 filed in Japan on Sep. 10, 2012 and based on PCT/JP2013/073679 filed on Sep. 3, 2013. The contents of both the Japanese Patent Application and the PCT Application are incorporated herein by reference.
2. Description of Related Art
The treatment of endoscopically incising living body tissues, such as a mucous membrane, is performed using an endoscope treatment tool including a knife unit (rod-shaped electrode) to which a high-frequency voltage is supplied. As such an endoscope treatment tool, for example, a high-frequency knife disclosed in Japanese Patent No. 4455002 is known.
In this high-frequency knife, a small-diameter rod-shaped first electrode portion is arranged so as to protrude from a distal end of a sheath in an axial direction of the sheath. A distal end portion of the first electrode portion is provided with a second electrode portion radially extending in a direction orthogonal to an axial direction of the first electrode portion. A knife unit is constituted by the first electrode portion and the second electrode portion.
Electrical insulator portions (chips) are provided at distal end portions of the first electrode portion and the second electrode portion.
In the high-frequency knife configured in this way, if the whole knife unit is moved in a transverse direction (a direction orthogonal to an axial direction of the knife unit) while supplying a high-frequency current to the knife unit, a mucous membrane contacting the first electrode portion is incised by the first electrode portion. When it is difficult to move the knife unit in the transverse direction, the whole knife unit is moved in a longitudinal direction (the axial direction of the knife unit). Then, the mucous membrane hooked and lifted by the second electrode portion is incised by the second electrode portion.
In the high-frequency knife disclosed in Japanese Patent No. 4455002, in order to fix the knife unit to the electrical insulator portion, the distal end portion of the knife unit may be attached to the concave portion formed in a proximal end surface of an electrical insulator portion with an adhesive or the like.
A connecting portion between the electrical insulator portion and the knife unit has a high temperature of hundreds of degrees Celcius due to the high-frequency current, and receives reaction forces in various directions when a living body tissue is excised. For this reason, there is a risk that the electrical insulator portion may fall off the knife unit.
In order to solve this problem, a high-frequency treatment tool disclosed in Japanese Unexamined Patent Application, First Publication No. 2007-21024 is suggested.
In the high-frequency treatment tool of Japanese Unexamined Patent Application, First Publication No. 2007-21024, a distal end portion of an electrode unit for treatment that is a knife unit is provided with a retaining portion including a protrusion or a concave portion. After this retaining portion is arranged in an electrical insulating portion forming space constituted by a fixed mold and a movable mold, a melted resin material is filled into an electrical insulating portion forming space. An electrical insulating portion (chip) is formed at the distal end portion of the electrode unit for treatment by cooling and solidifying this resin material.
Additionally, Japanese Unexamined Patent Application, First Publication No. 2007-21024 discloses that a swelling portion having a greater diameter than the external diameter dimension of the electrode unit for treatment is provided at the distal end side portion of the electrode unit for treatment, and the swelling portion is covered with a swelling portion covering insulator cover (chip) constituted by a pair of insulating cover members. By constituting the swelling portion covering insulator cover from the pair of insulating cover member, a shape engaged with the retaining portion of the electrode unit for treatment can be formed in the swelling portion covering insulator cover. Each insulating cover member is joined to the swelling portion by, for example, brazing.